<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        *{
            margin: 0px;
            padding: 0px;
        }
        .left{
            width: 400px;
            height: 300px;
            background-color:gold;
            float: left;
        }
        .right{
            height: 300px;
            background-color: skyblue;
        }
    </style>
</head>
<body>
    <div class="left"></div>
    <div class="right">ABC</div>
</body>
</html>